In the related art, as described in the following Patent Document 1, a liquid-sealed type vibration isolator including a first fixture, a cylindrical second fixture, a vibration-isolating base member formed of a rubbery elastic material for coupling the first fixture and the second fixture, a diaphragm formed of a rubber membrane which is mounted to the second fixture and defines a liquid-sealed chamber between the vibration-isolating base member and itself, a partitioning member configured to partition the liquid-sealed chamber into a first liquid chamber on the side of the vibration-isolating base member and a second liquid chamber on the side of the diaphragm, and an orifice configured to communicate the first liquid chamber and the second liquid chamber. In the liquid-sealed type vibration isolator, the partitioning member is configured with an elastic partitioning membrane, an annular orifice forming member configured to accommodate the elastic partitioning membrane, and a first lattice portion and a second lattice portion configured to restrict the amount of displacement of the membrane surface of the elastic partitioning membrane from both sides.
In the liquid-sealed type vibration isolator, when low-frequency vibrations having large amplitude occur, liquid circulates between the first liquid chamber and the second liquid chamber through the orifice, and damps the vibrations by the liquid flow effect. When high-frequency vibrations having minute amplitude occur, the elastic partitioning membrane are deformed in a reciprocating motion, so that the liquid pressure in the first liquid chamber is absorbed to reduce the vibrations. According to the structure in the related art, there is a problem such that an impact caused by a collision of the elastic partitioning membrane against the first lattice portion and the second lattice portion is transmitted to the second fixture via the orifice forming member formed of a stiff member, and then from the second fixture to the vehicle body side, thereby generating an abnormal sound in a cabin.
In contrast, in the following Patent Document 2 and Patent Document 3, for the purpose of preventing the abnormal sound caused by an impact from being transmitted to the cabin without loss of the vibration-isolating characteristics, the configuration of the partitioning member that partitions the first liquid chamber and the second liquid chamber as follows. In other words, the partitioning member includes the annular orifice forming member, a rubber wall configured to close an inner peripheral surface of the orifice forming member, a pair of partitioning plates connected to each other via a coupling portion which penetrates through the rubber wall and hold the rubber wall therebetween in the axial direction so that the amount of displacement of the pair of partitioning plates in the axial direction is restricted by the rubber wall.    Patent Document 1: JP-A-2006-342834    Patent Document 2: JP-A-2006-207672    Patent Document 3: JP-A-2007-211971